As organizations and individuals interact over ever-increasing distances, and communication technology advances and becomes less expensive, more and more people are using video conferencing systems. An important part of a typical video conferencing system is a multi-point conference unit (MCU) (also sometimes referred to as a multipoint control unit). An MCU is a device that enables conference endpoints (such as a video telephone, a video-enabled personal computer, etc.) to connect together.
Typically, MCUs are limited in the number of endpoints that can be connected to them. For example, an MCU may be limited to connecting ten endpoints. In order to have larger conferences than ten users, it is necessary to either obtain a larger MCU, or to cascade two or more smaller MCUs. Cascading is a process by which the two or more MCUs can communicate, and thus enable the endpoints connected to each to communicate (at least to some extent).
Cascading may also be used to decrease bandwidth on a wide area network (WAN) when a first set of users (who are local to each other) are connected to an MCU that is remotely located from the users and perhaps connected to a second set of users local to the MCU. For example, with a cascaded arrangement, such first users may be able to connect to a first MCU that is local to them (e.g., via a local area network), and that MCU may be able to connect, via a wide area network, to a second MCU that is remotely located from the first MCU. The first MCU may then locally handle the transfer of video between the first users, while the wide area network may only need to handle video being transmitted between the first set of users and the second set of users.
Current techniques for cascading MCUs, however, can present difficulties when different configurations of parameters (such as bit rate, frame rate, resolution, etc.) are required by one or more of the cascaded MCUs, or the endpoints connected to them.